Blue Portance Expert Guides

Understanding Pain

The biological, mechanical, and neurophysiological mechanisms that explain the onset and persistence of sitting-related pain.

This article is part of the Expert Guide “Understanding Pain”.

Nociceptive Pain: When Stress Exceeds a Tissue’s Adaptive Capacity

Epistemic note — This article is part of the “Understanding Pain” Expert Guide of the Blue Portance Knowledge Base: the concepts defined here form the foundation used throughout the Expert Guides, frequently asked questions, real-life situations, and case studies. In addition, it distinguishes between knowledge established in the scientific literature, the biomechanical model proposed by Blue Portance, and hypotheses or clinical observations that are not yet the subject of an established consensus. Finally, it aims to explain general mechanisms and does not constitute a diagnosis or a medical prescription.

Nociceptive pain arises when nociceptors are activated by an actual or potential threat to non-neural tissues. From a biomechanical perspective, this activation can be understood as the result of an interaction between a stress, the tissue that receives it, its adaptive capacity, and the length of time the loading is sustained. A visible lesion is therefore not always necessary: deformation, inflammation, local ischemia, or prolonged stress may be enough to produce or amplify nociceptive activity — this is notably what is at play in the soft tissues beneath the ischial tuberosities and in the lumbar fascia during prolonged sitting.

Why this article matters

The article “The Three Mechanisms of Pain” distinguishes between nociceptive, neuropathic, and nociplastic mechanisms. This article, for its part, examines the first of them in depth: it seeks not only to define nociceptive painNociceptive painNociceptive pain is pain related to actual or threatened damage to non-neural tissue, resulting from the activation of nociceptors. The somatosensory nervous system is functioning normally.Read the full entry : Nociceptive pain, but to understand how a load becomes capable of activating nociceptors, particularly in the tissues that sitting actually puts to work.

The central question is therefore not simply “Is the tissue damaged?” but rather:

what stress is acting, on which tissue, at what intensity, for how long, and with what opportunity for recovery?

In practice, this way of reasoning helps explain why the same pressure, the same movement, or the same posture can be well tolerated at one moment and become painful at another.

1. What “nociceptive pain” means

IASP terminology

Nociceptive pain is associated with actual or potential damage to non-neural tissue and results from the activation of nociceptors. It differs, however, from neuropathic painNeuropathic painNeuropathic pain is pain caused by a lesion or disease of the somatosensory nervous system.Read the full entry : Neuropathic pain, which implies a lesion or disease of the somatosensory nervous system.

Nociceptors are specialized sensory nerve endings capable of detecting potentially threatening mechanical, thermal, or chemical stimuli. When activated, they produce signals that are transmitted to the spinal cord and then to brain structures, where this information is modulated and integrated (Basbaum et al., 2009; Dubin & Patapoutian, 2010).

NociceptionNociceptionNociception is the process by which the nervous system detects and encodes stimuli that are potentially damaging to tissues. It is not the same as pain, which is an experience.Read the full entry : Nociception, however, is not pain itself. In concrete terms, it refers to the activity of the sensory system that detects and transmits a potential threat. Pain, for its part, is the experience that results from integrating this activity with other biological, contextual, and personal information.

Diagram showing how mechanical stress can exceed tissue adaptive capacity, activate nociceptors, and contribute to nociceptive pain. — Figure 1 — How stress becomes nociceptive pain Mechanical stress does not automatically cause pain. In reality, pain arises when the tissue’s local adaptive capacity is exceeded, triggering nociceptor activation and the transmission of a pain signal.

2. From stress to tissue: the first step in the mechanism

Nociceptive pain can be triggered by several families of stimuli, among others:

mechanical: pressure, compression, tension, shearShearShear is a deformation produced by forces parallel or tangential to a surface, which cause neighboring layers or regions of a tissue to slide relative to one another.Read the full entry : Shear, friction, impact, or repeated deformation;
thermal: for example, heat or cold capable of threatening tissue integrity;
chemical: notably mediators released during inflammation, cellular injury, or a local metabolic disturbance.

Diagram showing pressure, compression, tension, shear, friction, and other mechanical stresses that can load biological tissues. — Figure 2 — Mechanical stresses applied to tissues The main mechanical stresses likely to load tissues. Together, their intensity, duration, repetition, and distribution determine the tissue response.

In sitting-related pain, stresses are therefore often mechanical and time-dependent. Pressure can remain tolerable when it is brief, but become problematic if it is concentrated on a small area, sustained without variation, or repeated before the tissue has recovered.

Many structures can contribute to nociceptive activity: skin, subcutaneous tissue, muscles, tendons, entheses, ligaments, joint capsules, fasciaFasciaFascia are connective tissue structures that envelop, connect or separate certain parts of the body. The "fascial system" refers to a broader set of connective tissues considered in their functional continuity.Read the full entry : Fascia, periosteum, and the connective tissue sheaths of nerves. Moreover, their involvement cannot be inferred from the name of the pain alone; it depends on the location, the triggers, the timing, and the anatomical consistency of the situation. In the specific context of sitting, two areas notably concentrate these stresses: the soft tissues beneath the ischial tuberosities — skin, subcutaneous fat, fascia, and neighboring ligamentous structures, including the sacrotuberous ligaments — which bear most of the weight of the upper body; and the lumbar and thoracolumbar fasciaThoracolumbar fasciaThe thoracolumbar fascia is a set of connective tissue layers in the lower back. It envelops the deep back muscles and receives the attachments or extensions of several muscles of the trunk and pelvis.Read the full entry : Thoracolumbar fascia, loaded by the prolonged maintenance of a posture with little variation.

Example: ischial compression during prolonged sitting

When sitting, the weight of the upper body is concentrated notably on a small area: the soft tissues beneath the ischial tuberosities. When sitting is prolonged and varies little, and the weight distribution remains concentrated on the same contact points, several of the dimensions described below combine: high local intensity, prolonged duration, repetition without real recovery, and poorly diffused distribution. Together, these factors may then be enough to activate nociceptors present in these tissues, without any structural lesion necessarily being involved.

Likewise, this reasoning applies to the lumbar and thoracolumbar fascia: maintaining a seated posture with little variation limits its natural gliding and concentrates stress on the same fibers, which may, over time, contribute to the activation or sensitization of its own nociceptors (Schleip et al., 2012) — a mechanism discussed more broadly in the article “Nervous System Hypersensitization”.

3. Tissue adaptive capacity

Proposed biomechanical framework

Tissue adaptive capacity here refers to a structure’s ability to withstand, distribute, or compensate for stress while maintaining a function compatible with the situation.

This concept does not correspond to a fixed value. Rather, it serves to organize several dimensions that determine the effect of a given load:

Diagram illustrating the relationship between mechanical stress and a tissue’s adaptive capacity. — Figure 3 — Tissue adaptive capacity Tissue adaptive capacity is the central element of the nociceptive mechanism. As long as stresses remain compatible with the tissue’s capacity to adapt, no pain signal is generated.

Dimension	Question to ask	Possible effect
Intensity	What force or pressure is applied?	High intensity can then quickly exceed local capacity.
Duration	How long does the stress remain applied?	Moderate stress can, as a result, become problematic when it is prolonged.
Repetition	Does the loading recur before recovery?	Successive episodes can then accumulate their effects.
Distribution	Is the load diffuse or concentrated?	Concentrating it therefore increases local stress.
Variability	Do contact points and movements change?	A lack of variation thus prolongs the loading of the same structures.
Tissue condition	Is there inflammation, fatigue, a scar, or pre-existing vulnerability?	The response threshold may, consequently, be lowered.
Recovery	Does the tissue have enough time and adequate conditions to recover?	Insufficient recovery may, in effect, promote persistent sensitivity.

The same stress does not always produce the same response

Pressure can be painless when it is brief, distributed, and followed by sufficient recovery. Conversely, it can become painful when it is concentrated, prolonged, or acts on an already sensitized structure. Variability in the response therefore does not mean that the pain is arbitrary: it reflects the interaction between the stress, the tissue, and the biological context in which it occurs.

4. Why do duration and repetition change the situation?

A load is not defined solely by its peak intensity. In fact, its effect depends on how it unfolds over time.

Prolonged stress can maintain a deformation, limit local exchanges, increase interstitial pressure, or reduce the capacity for gliding between certain structures. Repeated stress, for its part, can load the same area several times before local processes have had time to return to normal.

This time dimension helps explain two frequently observed patterns:

immediate pain: pressure, contact, or movement quickly reproduces the pain;
progressive pain: the area is tolerable at first, then becomes painful with duration, repetition, or fatigue.

These patterns guide the reasoning, but they are not sufficient on their own to identify the mechanism. Neuropathic or nociplastic painNociplastic painNociplastic pain is pain arising from altered nociception, without clear evidence of tissue damage activating nociceptors, or of a lesion or disease of the somatosensory system sufficient to explain the pain.Read the full entry : Nociplastic pain can also be influenced by posture or by the duration of exposure.

5. Peripheral sensitization: when the response threshold drops

When a tissue is inflamed or exposed to certain chemical mediators, nociceptors can become more reactive. As a result, their activation threshold decreases and their response to a stimulus may increase. This phenomenon is called peripheral sensitizationPeripheral sensitizationPeripheral sensitization is increased responsiveness and reduced threshold of peripheral nociceptive neurons to the stimulation of their receptive fields (IASP definition).Read the full entry : Peripheral sensitization (Gold & Gebhart, 2010).

A previously well-tolerated stimulus may then become painful, and an already painful stimulus may produce a more intense response. This change remains compatible with a nociceptive mechanism: it reflects increased reactivity of the peripheral nerve endings, without in itself implying a lesion of the somatosensory system or nociplastic pain.

Diagram showing how inflammatory or chemical mediators can lower nociceptor activation thresholds and increase their responsiveness. — Figure 4 — Peripheral sensitization of nociceptors Peripheral sensitization increases the reactivity of nociceptors. The same stimulus can then produce a greater pain response.

6. Can nociceptive pain exist without a visible lesion?

Yes. The international definition refers to actual or potential damage to non-neural tissues. Sustained deformation, local inflammation, transient ischemia, or a functional disturbance can activate or sensitize nociceptors without producing a tear or a detectable macroscopic abnormality.

Conversely, an abnormality visible on imaging can remain silent. Imaging describes certain anatomical features; it measures neither nociceptor activity nor the intensity of the pain experience.

What not to conclude

Normal imaging does not prove the absence of a nociceptive mechanism.
Likewise, a visible abnormality does not prove that it explains all of the pain.
Moreover, intense pain does not provide a direct measure of the extent of a lesion.
Finally, pain triggered by a posture is not enough to rule out a neuropathic or nociplastic component.
The exact role of fascia in producing pain remains debated: is it a primary generator through its own nociceptors, or merely an amplifier of stresses transmitted from other structures (Schleip et al., 2012)? Current evidence leans toward a mixed role, without settling the question definitively.

7. The interpretation proposed by the Blue Portance biomechanical model

The Blue Portance biomechanical model does not propose a new definition of nociceptive pain. Rather, it seeks to connect the existing definition to the concrete organization of stresses.

stress → tissue → adaptive capacity → nociceptive activity → transmission and modulation → pain → behavior → adaptation

Diagram linking mechanical stress, tissue adaptive capacity, nociceptive activity, neural transmission, and pain. — Figure 5 — A biomechanical reading of nociceptive pain Biomechanical interpretation proposed by Blue Portance. In practice, the model links the organization of stresses, tissue adaptive capacity, and the onset of nociceptive activity that may be perceived as pain.

This interpretation rests on four complementary questions:

What is the nature of the stress? For example, compression, tension, shear, friction, vibration, or a combination of several loads.
Which structure receives it? Skin, muscle, tendon, fascia, ligament, capsule, periosteum, or the sheaths of a nerve.
How does the stress evolve over time? Immediate onset, progressive accumulation, repetition, or lack of variation.
What are the possibilities for adaptation and recovery? Distribution of contact points, available mobility, alternation of positions, and the prior condition of the tissues.

In sitting-related pain, this framework notably leads to examining whether an area bears overly concentrated pressure — typically beneath the ischial tuberosities —, whether contact points remain monotonous, whether the lumbar fascia is placed under prolonged tension, or whether pain appears only after a certain duration of exposure.

8. Practical implications for understanding pain

In concrete terms, a nociceptive hypothesis leads one to look for a consistent relationship between a stress and a structure, without reducing the reasoning to the presence of a lesion.

Location: does the pain correspond to an anatomically plausible area?
Trigger: do contact, pressure, movement, or posture reproduce it?
Timing: does it appear immediately or increase progressively?
Reversibility: does it decrease when the stress is removed, distributed, or modified?
Local tissue context: is there inflammation, a scar, fatigue, fragility, or pre-existing sensitivity?
Associated mechanisms: do certain signs also suggest somatosensory damage or more broadly altered nociception?

This framework does not establish a diagnosis. Rather, it organizes the analysis and avoids two opposite errors: attributing all pain to a visible lesion, or dismissing a peripheral contribution too quickly when no major abnormality is found.

Key takeaways

Nociceptive pain involves the activation of nociceptors by an actual or potential threat to non-neural tissues.
Nociception and pain are related, but the two terms are not interchangeable.
Moreover, the effect of a stress depends on its intensity, duration, repetition, and distribution, and on the condition of the tissue.
When sitting, the soft tissues beneath the ischial tuberosities and the lumbar fascia notably concentrate these stresses.
Moderate stress can thus become painful when it is prolonged or repeated without sufficient recovery.
Nociceptive pain can, however, exist without a visible macroscopic lesion.
In addition, peripheral sensitization lowers the response threshold of nociceptors.
Finally, the Blue Portance model links the definition of the mechanism to the nature of the stresses, adaptive capacity, and timing.

Frequently asked questions

Does nociceptive pain imply a visible lesion?

No. Stress, inflammation, local ischemia, or sustained deformation can activate or sensitize nociceptors without producing a macroscopic lesion visible on standard diagnostic testing.

Why can moderate stress become painful over time?

Because the effect of a stress also depends on its duration, its repetition, the recovery available, and the condition of the tissue. A stress tolerated briefly can thus exceed local capacity when it is prolonged.

Is nociceptive pain always proportional to a lesion?

No. Pain intensity depends on nociceptive activity, but also on how the nervous system modulates and integrates it. It is therefore not a direct measure of the extent of a lesion.

Is pain caused by sitting necessarily nociceptive?

No. A link with a posture or with pressure is a mechanical clue, but it is not enough to determine the mechanism. Moreover, pain can combine nociceptive, neuropathic, or nociplastic components.

Trying to understand what keeps your pain going when you sit?

The analysis draws notably on location, stresses, timing, the structures involved, and the mechanisms likely to combine.

Analyze my situation →

Note: this content explains general mechanisms of nociceptive pain. It therefore cannot determine remotely the mechanism of an individual’s pain and does not replace the advice of a healthcare professional.

Scientific references

International Association for the Study of Pain (IASP). IASP Terminology. Official terminology.
Basbaum AI, Bautista DM, Scherrer G, Julius D. Cellular and molecular mechanisms of pain. Cell. 2009;139(2):267–284. doi:10.1016/j.cell.2009.09.028.
Dubin AE, Patapoutian A. Nociceptors: the sensors of the pain pathway. Journal of Clinical Investigation. 2010;120(11):3760–3772. doi:10.1172/JCI42843.
Gold MS, Gebhart GF. Nociceptor sensitization in pain pathogenesis. Nature Medicine. 2010;16(11):1248–1257. doi:10.1038/nm.2235.
Schleip, R., et al. Fascia as a sensory organ. In: Fascia: The Tensional Network of the Human Body. Churchill Livingstone / Elsevier, 2012.